Protéinose alvéolaire pulmonaire congénitale en rapport avec un déficit en protéine B du surfactant : à propos de deux observations

Congenital pulmonary alveolar proteinosis is an uncommon affection, distinct from adult's alveolar proteinosis by its clinical, pathological, etiological and evolutive characteristics. We report two cases of congenital alveolar proteinosis related to a surfactant protein B deficiency. Clinical presentations were similar: the two children were full-term newborns and had swiftly developed respiratory distress. Chest radiography demonstrated bilateral alveolar syndrome. Echocardiography was normal. There was no sign of infection. The two children died respectively at three weeks and two months of life. Lung biopsy showed lesions of alveolar proteinosis in the two cases. Both children were homozygotes for the 121ins2 mutation of the SFTPB gene. Diagnosis of surfactant protein B deficiency must be suspected in congenital alveolar proteinosis. It can be confirmed by the absence of detection of the surfactant B protein by immunohistochemistry on fixed and paraffin-embedded lung tissue or by western blot on bronchoalveolar fluid and by the absence of mRNA by RT-PCR. We report the value of molecular diagnosis for genetic counseling and the possibility of early prenatal diagnosis by trophoblast biopsy.